LCOV - code coverage report
Current view: top level - src/backend/main - main.c (source / functions) Hit Total Coverage
Test: PostgreSQL 18devel Lines: 103 119 86.6 %
Date: 2025-04-02 20:15:43 Functions: 6 7 85.7 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * main.c
       4             :  *    Stub main() routine for the postgres executable.
       5             :  *
       6             :  * This does some essential startup tasks for any incarnation of postgres
       7             :  * (postmaster, standalone backend, standalone bootstrap process, or a
       8             :  * separately exec'd child of a postmaster) and then dispatches to the
       9             :  * proper FooMain() routine for the incarnation.
      10             :  *
      11             :  *
      12             :  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
      13             :  * Portions Copyright (c) 1994, Regents of the University of California
      14             :  *
      15             :  *
      16             :  * IDENTIFICATION
      17             :  *    src/backend/main/main.c
      18             :  *
      19             :  *-------------------------------------------------------------------------
      20             :  */
      21             : #include "postgres.h"
      22             : 
      23             : #include <unistd.h>
      24             : 
      25             : #if defined(WIN32)
      26             : #include <crtdbg.h>
      27             : #endif
      28             : 
      29             : #if defined(__NetBSD__)
      30             : #include <sys/param.h>
      31             : #endif
      32             : 
      33             : #include "bootstrap/bootstrap.h"
      34             : #include "common/username.h"
      35             : #include "miscadmin.h"
      36             : #include "postmaster/postmaster.h"
      37             : #include "tcop/tcopprot.h"
      38             : #include "utils/help_config.h"
      39             : #include "utils/memutils.h"
      40             : #include "utils/pg_locale.h"
      41             : #include "utils/ps_status.h"
      42             : 
      43             : 
      44             : const char *progname;
      45             : static bool reached_main = false;
      46             : 
      47             : /* names of special must-be-first options for dispatching to subprograms */
      48             : static const char *const DispatchOptionNames[] =
      49             : {
      50             :     [DISPATCH_CHECK] = "check",
      51             :     [DISPATCH_BOOT] = "boot",
      52             :     [DISPATCH_FORKCHILD] = "forkchild",
      53             :     [DISPATCH_DESCRIBE_CONFIG] = "describe-config",
      54             :     [DISPATCH_SINGLE] = "single",
      55             :     /* DISPATCH_POSTMASTER has no name */
      56             : };
      57             : 
      58             : StaticAssertDecl(lengthof(DispatchOptionNames) == DISPATCH_POSTMASTER,
      59             :                  "array length mismatch");
      60             : 
      61             : static void startup_hacks(const char *progname);
      62             : static void init_locale(const char *categoryname, int category, const char *locale);
      63             : static void help(const char *progname);
      64             : static void check_root(const char *progname);
      65             : 
      66             : 
      67             : /*
      68             :  * Any Postgres server process begins execution here.
      69             :  */
      70             : int
      71        3600 : main(int argc, char *argv[])
      72             : {
      73        3600 :     bool        do_check_root = true;
      74        3600 :     DispatchOption dispatch_option = DISPATCH_POSTMASTER;
      75             : 
      76        3600 :     reached_main = true;
      77             : 
      78             :     /*
      79             :      * If supported on the current platform, set up a handler to be called if
      80             :      * the backend/postmaster crashes with a fatal signal or exception.
      81             :      */
      82             : #if defined(WIN32)
      83             :     pgwin32_install_crashdump_handler();
      84             : #endif
      85             : 
      86        3600 :     progname = get_progname(argv[0]);
      87             : 
      88             :     /*
      89             :      * Platform-specific startup hacks
      90             :      */
      91        3600 :     startup_hacks(progname);
      92             : 
      93             :     /*
      94             :      * Remember the physical location of the initially given argv[] array for
      95             :      * possible use by ps display.  On some platforms, the argv[] storage must
      96             :      * be overwritten in order to set the process title for ps. In such cases
      97             :      * save_ps_display_args makes and returns a new copy of the argv[] array.
      98             :      *
      99             :      * save_ps_display_args may also move the environment strings to make
     100             :      * extra room. Therefore this should be done as early as possible during
     101             :      * startup, to avoid entanglements with code that might save a getenv()
     102             :      * result pointer.
     103             :      */
     104        3600 :     argv = save_ps_display_args(argc, argv);
     105             : 
     106             :     /*
     107             :      * Fire up essential subsystems: error and memory management
     108             :      *
     109             :      * Code after this point is allowed to use elog/ereport, though
     110             :      * localization of messages may not work right away, and messages won't go
     111             :      * anywhere but stderr until GUC settings get loaded.
     112             :      */
     113        3600 :     MyProcPid = getpid();
     114        3600 :     MemoryContextInit();
     115             : 
     116             :     /*
     117             :      * Set reference point for stack-depth checking.  (There's no point in
     118             :      * enabling this before error reporting works.)
     119             :      */
     120        3600 :     (void) set_stack_base();
     121             : 
     122             :     /*
     123             :      * Set up locale information
     124             :      */
     125        3600 :     set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("postgres"));
     126             : 
     127             :     /*
     128             :      * In the postmaster, absorb the environment values for LC_COLLATE and
     129             :      * LC_CTYPE.  Individual backends will change these later to settings
     130             :      * taken from pg_database, but the postmaster cannot do that.  If we leave
     131             :      * these set to "C" then message localization might not work well in the
     132             :      * postmaster.
     133             :      */
     134        3600 :     init_locale("LC_COLLATE", LC_COLLATE, "");
     135        3600 :     init_locale("LC_CTYPE", LC_CTYPE, "");
     136             : 
     137             :     /*
     138             :      * LC_MESSAGES will get set later during GUC option processing, but we set
     139             :      * it here to allow startup error messages to be localized.
     140             :      */
     141             : #ifdef LC_MESSAGES
     142        3600 :     init_locale("LC_MESSAGES", LC_MESSAGES, "");
     143             : #endif
     144             : 
     145             :     /* We keep these set to "C" always.  See pg_locale.c for explanation. */
     146        3600 :     init_locale("LC_MONETARY", LC_MONETARY, "C");
     147        3600 :     init_locale("LC_NUMERIC", LC_NUMERIC, "C");
     148        3600 :     init_locale("LC_TIME", LC_TIME, "C");
     149             : 
     150             :     /*
     151             :      * Now that we have absorbed as much as we wish to from the locale
     152             :      * environment, remove any LC_ALL setting, so that the environment
     153             :      * variables installed by pg_perm_setlocale have force.
     154             :      */
     155        3600 :     unsetenv("LC_ALL");
     156             : 
     157             :     /*
     158             :      * Catch standard options before doing much else, in particular before we
     159             :      * insist on not being root.
     160             :      */
     161        3600 :     if (argc > 1)
     162             :     {
     163        3600 :         if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
     164             :         {
     165           2 :             help(progname);
     166           2 :             exit(0);
     167             :         }
     168        3598 :         if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
     169             :         {
     170        1466 :             fputs(PG_BACKEND_VERSIONSTR, stdout);
     171        1466 :             exit(0);
     172             :         }
     173             : 
     174             :         /*
     175             :          * In addition to the above, we allow "--describe-config" and "-C var"
     176             :          * to be called by root.  This is reasonably safe since these are
     177             :          * read-only activities.  The -C case is important because pg_ctl may
     178             :          * try to invoke it while still holding administrator privileges on
     179             :          * Windows.  Note that while -C can normally be in any argv position,
     180             :          * if you want to bypass the root check you must put it first.  This
     181             :          * reduces the risk that we might misinterpret some other mode's -C
     182             :          * switch as being the postmaster/postgres one.
     183             :          */
     184        2132 :         if (strcmp(argv[1], "--describe-config") == 0)
     185           0 :             do_check_root = false;
     186        2132 :         else if (argc > 2 && strcmp(argv[1], "-C") == 0)
     187           2 :             do_check_root = false;
     188             :     }
     189             : 
     190             :     /*
     191             :      * Make sure we are not running as root, unless it's safe for the selected
     192             :      * option.
     193             :      */
     194        2132 :     if (do_check_root)
     195        2130 :         check_root(progname);
     196             : 
     197             :     /*
     198             :      * Dispatch to one of various subprograms depending on first argument.
     199             :      */
     200             : 
     201        2132 :     if (argc > 1 && argv[1][0] == '-' && argv[1][1] == '-')
     202         458 :         dispatch_option = parse_dispatch_option(&argv[1][2]);
     203             : 
     204        2132 :     switch (dispatch_option)
     205             :     {
     206         240 :         case DISPATCH_CHECK:
     207         240 :             BootstrapModeMain(argc, argv, true);
     208             :             break;
     209          98 :         case DISPATCH_BOOT:
     210          98 :             BootstrapModeMain(argc, argv, false);
     211             :             break;
     212           0 :         case DISPATCH_FORKCHILD:
     213             : #ifdef EXEC_BACKEND
     214             :             SubPostmasterMain(argc, argv);
     215             : #else
     216             :             Assert(false);      /* should never happen */
     217             : #endif
     218           0 :             break;
     219           0 :         case DISPATCH_DESCRIBE_CONFIG:
     220           0 :             GucInfoMain();
     221             :             break;
     222         118 :         case DISPATCH_SINGLE:
     223         118 :             PostgresSingleUserMain(argc, argv,
     224         118 :                                    strdup(get_user_name_or_exit(progname)));
     225             :             break;
     226        1676 :         case DISPATCH_POSTMASTER:
     227        1676 :             PostmasterMain(argc, argv);
     228             :             break;
     229             :     }
     230             : 
     231             :     /* the functions above should not return */
     232           0 :     abort();
     233             : }
     234             : 
     235             : /*
     236             :  * Returns the matching DispatchOption value for the given option name.  If no
     237             :  * match is found, DISPATCH_POSTMASTER is returned.
     238             :  */
     239             : DispatchOption
     240        1946 : parse_dispatch_option(const char *name)
     241             : {
     242        9966 :     for (int i = 0; i < lengthof(DispatchOptionNames); i++)
     243             :     {
     244             :         /*
     245             :          * Unlike the other dispatch options, "forkchild" takes an argument,
     246             :          * so we just look for the prefix for that one.  For non-EXEC_BACKEND
     247             :          * builds, we never want to return DISPATCH_FORKCHILD, so skip over it
     248             :          * in that case.
     249             :          */
     250        8476 :         if (i == DISPATCH_FORKCHILD)
     251             :         {
     252             : #ifdef EXEC_BACKEND
     253             :             if (strncmp(DispatchOptionNames[DISPATCH_FORKCHILD], name,
     254             :                         strlen(DispatchOptionNames[DISPATCH_FORKCHILD])) == 0)
     255             :                 return DISPATCH_FORKCHILD;
     256             : #endif
     257        1608 :             continue;
     258             :         }
     259             : 
     260        6868 :         if (strcmp(DispatchOptionNames[i], name) == 0)
     261         456 :             return (DispatchOption) i;
     262             :     }
     263             : 
     264             :     /* no match means this is a postmaster */
     265        1490 :     return DISPATCH_POSTMASTER;
     266             : }
     267             : 
     268             : /*
     269             :  * Place platform-specific startup hacks here.  This is the right
     270             :  * place to put code that must be executed early in the launch of any new
     271             :  * server process.  Note that this code will NOT be executed when a backend
     272             :  * or sub-bootstrap process is forked, unless we are in a fork/exec
     273             :  * environment (ie EXEC_BACKEND is defined).
     274             :  *
     275             :  * XXX The need for code here is proof that the platform in question
     276             :  * is too brain-dead to provide a standard C execution environment
     277             :  * without help.  Avoid adding more here, if you can.
     278             :  */
     279             : static void
     280        3600 : startup_hacks(const char *progname)
     281             : {
     282             :     /*
     283             :      * Windows-specific execution environment hacking.
     284             :      */
     285             : #ifdef WIN32
     286             :     {
     287             :         WSADATA     wsaData;
     288             :         int         err;
     289             : 
     290             :         /* Make output streams unbuffered by default */
     291             :         setvbuf(stdout, NULL, _IONBF, 0);
     292             :         setvbuf(stderr, NULL, _IONBF, 0);
     293             : 
     294             :         /* Prepare Winsock */
     295             :         err = WSAStartup(MAKEWORD(2, 2), &wsaData);
     296             :         if (err != 0)
     297             :         {
     298             :             write_stderr("%s: WSAStartup failed: %d\n",
     299             :                          progname, err);
     300             :             exit(1);
     301             :         }
     302             : 
     303             :         /*
     304             :          * By default abort() only generates a crash-dump in *non* debug
     305             :          * builds. As our Assert() / ExceptionalCondition() uses abort(),
     306             :          * leaving the default in place would make debugging harder.
     307             :          *
     308             :          * MINGW's own C runtime doesn't have _set_abort_behavior(). When
     309             :          * targeting Microsoft's UCRT with mingw, it never links to the debug
     310             :          * version of the library and thus doesn't need the call to
     311             :          * _set_abort_behavior() either.
     312             :          */
     313             : #if !defined(__MINGW32__) && !defined(__MINGW64__)
     314             :         _set_abort_behavior(_CALL_REPORTFAULT | _WRITE_ABORT_MSG,
     315             :                             _CALL_REPORTFAULT | _WRITE_ABORT_MSG);
     316             : #endif                          /* !defined(__MINGW32__) &&
     317             :                                  * !defined(__MINGW64__) */
     318             : 
     319             :         /*
     320             :          * SEM_FAILCRITICALERRORS causes more errors to be reported to
     321             :          * callers.
     322             :          *
     323             :          * We used to also specify SEM_NOGPFAULTERRORBOX, but that prevents
     324             :          * windows crash reporting from working. Which includes registered
     325             :          * just-in-time debuggers, making it unnecessarily hard to debug
     326             :          * problems on windows. Now we try to disable sources of popups
     327             :          * separately below (note that SEM_NOGPFAULTERRORBOX did not actually
     328             :          * prevent all sources of such popups).
     329             :          */
     330             :         SetErrorMode(SEM_FAILCRITICALERRORS);
     331             : 
     332             :         /*
     333             :          * Show errors on stderr instead of popup box (note this doesn't
     334             :          * affect errors originating in the C runtime, see below).
     335             :          */
     336             :         _set_error_mode(_OUT_TO_STDERR);
     337             : 
     338             :         /*
     339             :          * In DEBUG builds, errors, including assertions, C runtime errors are
     340             :          * reported via _CrtDbgReport. By default such errors are displayed
     341             :          * with a popup (even with NOGPFAULTERRORBOX), preventing forward
     342             :          * progress. Instead report such errors stderr (and the debugger).
     343             :          * This is C runtime specific and thus the above incantations aren't
     344             :          * sufficient to suppress these popups.
     345             :          */
     346             :         _CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
     347             :         _CrtSetReportFile(_CRT_ERROR, _CRTDBG_FILE_STDERR);
     348             :         _CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
     349             :         _CrtSetReportFile(_CRT_ASSERT, _CRTDBG_FILE_STDERR);
     350             :         _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
     351             :         _CrtSetReportFile(_CRT_WARN, _CRTDBG_FILE_STDERR);
     352             :     }
     353             : #endif                          /* WIN32 */
     354        3600 : }
     355             : 
     356             : 
     357             : /*
     358             :  * Make the initial permanent setting for a locale category.  If that fails,
     359             :  * perhaps due to LC_foo=invalid in the environment, use locale C.  If even
     360             :  * that fails, perhaps due to out-of-memory, the entire startup fails with it.
     361             :  * When this returns, we are guaranteed to have a setting for the given
     362             :  * category's environment variable.
     363             :  */
     364             : static void
     365       21600 : init_locale(const char *categoryname, int category, const char *locale)
     366             : {
     367       21600 :     if (pg_perm_setlocale(category, locale) == NULL &&
     368           0 :         pg_perm_setlocale(category, "C") == NULL)
     369           0 :         elog(FATAL, "could not adopt \"%s\" locale nor C locale for %s",
     370             :              locale, categoryname);
     371       21600 : }
     372             : 
     373             : 
     374             : 
     375             : /*
     376             :  * Help display should match the options accepted by PostmasterMain()
     377             :  * and PostgresMain().
     378             :  *
     379             :  * XXX On Windows, non-ASCII localizations of these messages only display
     380             :  * correctly if the console output code page covers the necessary characters.
     381             :  * Messages emitted in write_console() do not exhibit this problem.
     382             :  */
     383             : static void
     384           2 : help(const char *progname)
     385             : {
     386           2 :     printf(_("%s is the PostgreSQL server.\n\n"), progname);
     387           2 :     printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
     388           2 :     printf(_("Options:\n"));
     389           2 :     printf(_("  -B NBUFFERS        number of shared buffers\n"));
     390           2 :     printf(_("  -c NAME=VALUE      set run-time parameter\n"));
     391           2 :     printf(_("  -C NAME            print value of run-time parameter, then exit\n"));
     392           2 :     printf(_("  -d 1-5             debugging level\n"));
     393           2 :     printf(_("  -D DATADIR         database directory\n"));
     394           2 :     printf(_("  -e                 use European date input format (DMY)\n"));
     395           2 :     printf(_("  -F                 turn fsync off\n"));
     396           2 :     printf(_("  -h HOSTNAME        host name or IP address to listen on\n"));
     397           2 :     printf(_("  -i                 enable TCP/IP connections (deprecated)\n"));
     398           2 :     printf(_("  -k DIRECTORY       Unix-domain socket location\n"));
     399             : #ifdef USE_SSL
     400           2 :     printf(_("  -l                 enable SSL connections\n"));
     401             : #endif
     402           2 :     printf(_("  -N MAX-CONNECT     maximum number of allowed connections\n"));
     403           2 :     printf(_("  -p PORT            port number to listen on\n"));
     404           2 :     printf(_("  -s                 show statistics after each query\n"));
     405           2 :     printf(_("  -S WORK-MEM        set amount of memory for sorts (in kB)\n"));
     406           2 :     printf(_("  -V, --version      output version information, then exit\n"));
     407           2 :     printf(_("  --NAME=VALUE       set run-time parameter\n"));
     408           2 :     printf(_("  --describe-config  describe configuration parameters, then exit\n"));
     409           2 :     printf(_("  -?, --help         show this help, then exit\n"));
     410             : 
     411           2 :     printf(_("\nDeveloper options:\n"));
     412           2 :     printf(_("  -f s|i|o|b|t|n|m|h forbid use of some plan types\n"));
     413           2 :     printf(_("  -O                 allow system table structure changes\n"));
     414           2 :     printf(_("  -P                 disable system indexes\n"));
     415           2 :     printf(_("  -t pa|pl|ex        show timings after each query\n"));
     416           2 :     printf(_("  -T                 send SIGABRT to all backend processes if one dies\n"));
     417           2 :     printf(_("  -W NUM             wait NUM seconds to allow attach from a debugger\n"));
     418             : 
     419           2 :     printf(_("\nOptions for single-user mode:\n"));
     420           2 :     printf(_("  --single           selects single-user mode (must be first argument)\n"));
     421           2 :     printf(_("  DBNAME             database name (defaults to user name)\n"));
     422           2 :     printf(_("  -d 0-5             override debugging level\n"));
     423           2 :     printf(_("  -E                 echo statement before execution\n"));
     424           2 :     printf(_("  -j                 do not use newline as interactive query delimiter\n"));
     425           2 :     printf(_("  -r FILENAME        send stdout and stderr to given file\n"));
     426             : 
     427           2 :     printf(_("\nOptions for bootstrapping mode:\n"));
     428           2 :     printf(_("  --boot             selects bootstrapping mode (must be first argument)\n"));
     429           2 :     printf(_("  --check            selects check mode (must be first argument)\n"));
     430           2 :     printf(_("  DBNAME             database name (mandatory argument in bootstrapping mode)\n"));
     431           2 :     printf(_("  -r FILENAME        send stdout and stderr to given file\n"));
     432             : 
     433           2 :     printf(_("\nPlease read the documentation for the complete list of run-time\n"
     434             :              "configuration settings and how to set them on the command line or in\n"
     435             :              "the configuration file.\n\n"
     436             :              "Report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
     437           2 :     printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
     438           2 : }
     439             : 
     440             : 
     441             : 
     442             : static void
     443        2130 : check_root(const char *progname)
     444             : {
     445             : #ifndef WIN32
     446        2130 :     if (geteuid() == 0)
     447             :     {
     448           0 :         write_stderr("\"root\" execution of the PostgreSQL server is not permitted.\n"
     449             :                      "The server must be started under an unprivileged user ID to prevent\n"
     450             :                      "possible system security compromise.  See the documentation for\n"
     451             :                      "more information on how to properly start the server.\n");
     452           0 :         exit(1);
     453             :     }
     454             : 
     455             :     /*
     456             :      * Also make sure that real and effective uids are the same. Executing as
     457             :      * a setuid program from a root shell is a security hole, since on many
     458             :      * platforms a nefarious subroutine could setuid back to root if real uid
     459             :      * is root.  (Since nobody actually uses postgres as a setuid program,
     460             :      * trying to actively fix this situation seems more trouble than it's
     461             :      * worth; we'll just expend the effort to check for it.)
     462             :      */
     463        2130 :     if (getuid() != geteuid())
     464             :     {
     465           0 :         write_stderr("%s: real and effective user IDs must match\n",
     466             :                      progname);
     467           0 :         exit(1);
     468             :     }
     469             : #else                           /* WIN32 */
     470             :     if (pgwin32_is_admin())
     471             :     {
     472             :         write_stderr("Execution of PostgreSQL by a user with administrative permissions is not\n"
     473             :                      "permitted.\n"
     474             :                      "The server must be started under an unprivileged user ID to prevent\n"
     475             :                      "possible system security compromises.  See the documentation for\n"
     476             :                      "more information on how to properly start the server.\n");
     477             :         exit(1);
     478             :     }
     479             : #endif                          /* WIN32 */
     480        2130 : }
     481             : 
     482             : /*
     483             :  * At least on linux, set_ps_display() breaks /proc/$pid/environ. The
     484             :  * sanitizer library uses /proc/$pid/environ to implement getenv() as it wants
     485             :  * to work independent of libc. When just using undefined and alignment
     486             :  * sanitizers, the sanitizer library is only initialized when the first error
     487             :  * occurs, by which time we've often already called set_ps_display(),
     488             :  * preventing the sanitizer libraries from seeing the options.
     489             :  *
     490             :  * We can work around that by defining __ubsan_default_options, a weak symbol
     491             :  * libsanitizer uses to get defaults from the application, and return
     492             :  * getenv("UBSAN_OPTIONS"). But only if main already was reached, so that we
     493             :  * don't end up relying on a not-yet-working getenv().
     494             :  *
     495             :  * As this function won't get called when not running a sanitizer, it doesn't
     496             :  * seem necessary to only compile it conditionally.
     497             :  */
     498             : const char *__ubsan_default_options(void);
     499             : const char *
     500           0 : __ubsan_default_options(void)
     501             : {
     502             :     /* don't call libc before it's guaranteed to be initialized */
     503           0 :     if (!reached_main)
     504           0 :         return "";
     505             : 
     506           0 :     return getenv("UBSAN_OPTIONS");
     507             : }

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